1. Field of the Invention:
The present invention relates to a needle locker in an overlock sewing machine for stitching hems of the cloth to prevent fraying of the hems of the cloth.
2. Description of the Prior Art:
In prior art overlock sewing machines, it is known that the hemstitching operation using a machine employing two needles with four threads can be switched to a machine using two needles with five threads. The overlock sewing machine for carrying out the hemstitching operation using two needles with four threads carries out the hemstitch of Stitching type #514 while the overlock sewing machine for carrying out the hemstitching operation using two needles with five threads carries out the hemstitch of Stitching type #516. The needle locker for carrying out the hemstitch using two needles with four threads employs two needles arranged in parallel across the cloth feeding direction while the needle locker for carrying out the hemstitch using two needles with five threads employs two needles arranged in the feeding direction and across the feeding direction in a predetermined interval.
However, the prior art overlock sewing machine exhibits a problem: at the time when the hemstitch operation using two needles and four threads is shifted to the hemstitch operation using two needles and five threads, a separate needle locker must be substituted despite the fact that one needle is mounted in the same position in a needle locker as the other needle. As a result, two needle lockers are required and additional time is required for substituting one locker for another.